The Preclinical Therapeutics Core (PCTC) facility generates tumor-bearing animals and conducts preclinical oncology trials for UCSF Comprehensive Cancer Center investigators. Offering a variety of xenograft-based cancer models, the core provides services that include consultation regarding experimental design, tumor cell growth in culture and generation of tumors in mice, administration of experimental agents, monitoring of tumor burden and response to therapy, and interpretation of study results. The PCTC maintains a cryorepository of commonly used human cancer cell lines derived from multiple tumor types along with data regarding their in vivo growth characteristics, and a user-accessible data base of genetically-engineered mouse models of human cancer maintained within the UCSF CCC, in order to foster collaboration between labs actively utilizing these models, and investigators interested in undertaking pre-clinical trials thereon. The PCTC is also a resource of expertise in small animal survival surgery, and is available to provide training in these techniques on a recharge basis. Although the core primarily functions to test experimental anti-cancer agents in vivo, it also provides animal models of human cancer for use in novel diagnostic, tumor, imaging, and basic mechanistic research. The core oversees, maintains and provides as a service a number of small animal imaging technologies housed within the barrier facility. The availability of centralized cell and animal resources, together with personnel with expertise in conducting preclinical studies, ensures appropriate experimental design and reproducibility, compliance with local and federal regulatory guidelines for tumorbearing animals, and maximum resource utilization through coordinated animal purchasing and housing.